1. they were doubtful that the cord would hold; it was doubtful whether she would be admitted; dubious about agreeing to go. 他们怀疑那条绳索能支撑住；她会不会被承认是充满疑问的；怀疑是否同意走。
2. Although Andre is doubtful that the plan will work, Victor is confident that Jack will come after them. 尽管安德烈怀疑这个计划是否行得通，维克多确信杰克会来找他们报仇的。
3. Method: In 107 patients with atypical chest pain and doubtful coronary heart disease, their quiet electrocardiogram were normal, and they examined exercise treadmill test. 方法：对107例不典型胸部疼痛的患者，平静心电图检查正常而临床疑似冠心病，行平板运动试验。
4. Miss Blanche goes abroad and marries in Paris a count with doubtful title. 布兰奇小姐出走国外，在巴黎与一个来路不明的伯爵结了婚。
5. Taxus L. is a problematic genus, not only its species are discouragingly similar, but also its family circumscription are still doubtful. 红豆杉种属的问题，不但它的种类惊人地相似，而且其科的界限也非常模糊。
